The present invention relates to a power control apparatus and a power control method for performing a power generation control of a generator which charges a battery to supply power to vehicle mounted electric components and performing a load restriction of the vehicle mounted electric components.
An electronic control unit (ECU) of a vehicle controls the vehicle by exchanging signals with control mechanisms of the vehicle. For example, when information such as a car speed, an engine RPM, the amount of air inflow and so on, which are detected by a sensor group equipped within a vehicle is input to an engine control ECU, the engine control ECU performs a predetermined calculation process based on the input information, and sends the calculated result (for example, a signal to control fuel injection amount, bypass air amount or the like) to the control mechanism, such as an electric throttle or a starter injection valve, equipped within the vehicle, to control the fuel injection amount, air inflow amount or the like.
In recent years, with rapid spread of automobiles, the number of automobile ECUs and vehicle mounted electric components have sharply increased to meet needs for improvement of comfort, safety, convenience and so on. For example, for a running system, there are the above-mentioned engine control ECU, a brake control ECU to control a brake, a steering control ECU to control steering, an economical running system to run a vehicle while activating and deactivating an engine, etc. In addition, for ensuring safety, there is a collision mitigation brake system (CMBS) (or a pre-crash system), an airbag system, an anti-brake system (ABS), a skidding protection system, etc. Also, for improving convenience, there is a push start system, a keyless system, an electromotive slide door, and for comfort, there is an AV system, an air conditioner, a navigation apparatus, etc.
In addition, for further improvement of comfort, convenience and safety in the future, the number of vehicle mounted electric components are expected to increase. Examples may include a road-to-vehicle communication system, a high performance driving system, an automatic drive system, an accident avoidance system, a collision avoidance system, a vehicle peripheral area monitoring system, etc. It can be expected that a battery will deteriorate with increased load on the battery, and will lack power with an increase in the number of electric components. Therefore, charging control of a battery to suppress deterioration of the battery and preventing disability of power feed in a vehicle condition is performed.
FIG. 16 is a view illustrating a charging control method. As shown in FIG. 16, if the amount of feeding indispensable power for a safety system, for example, a pre-crash system, an ABS, etc, is 1 KW, the amount of power required for electric components is 1.5 KW, and the amount of required battery charging is 0.5 KW, the amount of required power generation in a generator is 3 KW. In consideration of a vehicle running condition, the amount of power generation in the generator is determined to be 3 KW in deceleration of a vehicle and determined to be 2.5 KW in acceleration of the vehicle.
FIG. 17 is a view illustrating a power feeding restricting method. As shown in FIG. 17, if the amount of power generation in a generator is 1 KW, the amount of dischargeable electricity of a battery is 1 KW, and the amount of feeding indispensable power is 1 KW, the amount of power required for electric components is 1.5 KW, since a shortage 0.5 KW, power feeding to the electric components is restricted depending on using priority of the electric components with 0.5 KW as the amount of load limitation.
As mentioned above, the amount of power generation in the generator and the amount of power fed to the electric components have been controlled based on a battery condition, a running mode and the amount of necessary feeding electricity for the electric components. In Japanese Patent Publication No. 2001-505847A (corresponding U.S. Pat. No. 6,208,931, a running prediction unit is used and the amount of power generation is controlled based on the predicting result by the running prediction unit.
Specifically, as shown in FIG. 18, a prospective average engine RPM is calculated based on information from a navigation system, such as a running period, a road form, a road condition and the like, and, based on the prospective engine RPM and the battery condition, an evaluation is performed to execute energy management.
As described above, although the amount of power generation in the generator and the amount of power fed to the electric components have been controlled based on the battery condition, the running mode and the amount of necessary feeding electricity for the electric components, there is a problem that fuel efficiency is decreased due to the increased amount of power generation since the amount of feeding indispensable power is fixed and the amount of required power is calculated according to the maximum amount of feeding indispensable power irrespective of the running mode.
In addition, although the amount of power generation is controlled based on the predicting result by the running prediction unit, an energy distribution is determined based on only the average engine RPM and the battery condition. Accordingly, there is a possibility of disability of power feed or decrease of fuel efficiency since power generation cut by the running mode can not be considered with only the engine RPM.